a(n) = -3a(n-1) - 3a(n-2) - 2a(n-3), n > 3.

Terms

a(0) =2a(1) =2a(2) =2a(3) =-7a(4) =11a(5) =-16a(6) =29a(7) =-61a(8) =128a(9) =-259a(10) =515a(11) =-1024a(12) =2045a(13) =-4093a(14) =8192a(15) =-16387a(16) =32771a(17) =-65536a(18) =131069a(19) =-262141a(20) =524288a(21) =-1048579a(22) =2097155a(23) =-4194304a(24) =8388605a(25) =-16777213a(26) =33554432a(27) =-67108867a(28) =134217731a(29) =-268435456